1. Field of Invention
The present invention relates to a spot welding apparatus and, more particularly, to a spot welding apparatus which is commonly applicable to multiple classes by selecting a lower welding gun fitting a welding point of a welding target (i.e., a target to be welded) and performing a welding operation, and quickly performs a welding operation within a minimal time in a limited space.
2. Description of Related Art
In general, in manufacturing a vehicle, a vehicle body is completed by bonding various structure components such as a vehicle body panel, and the like, formed through pressing, painting and rustproofing operations are performed on surfaces of the respective components of the competed vehicle body during a painting process, components of a power train system and components of suspension, steering, and braking systems, and the like, are assembled, and an outfitting process of assembling doors, a trunk lid, a hood, and the like, is subsequently performed.
Also, during a vehicle body assembling process of a vehicle, a spot resistance welding through a spot welding apparatus is commonly used to bond two vehicle body panels in bonding vehicle body components such as a roof, a pillar, a side panel, an opening part flange of a vehicle body door, and the like.
Such spot resistance welding, a type of welding performed by applying welding force to a surface of a vehicle body panel, is generally performed by a spot welding apparatus installed in a front end of an arm of a spot welding robot.
A welding gun applied to the spot welding apparatus is classified into an X-type welding gun, a C-type welding gun, and a special type welding gun applied to a special lower arm according to whether a position of a welding part and a vehicle body are interfered.
A single spot welding apparatus selectively employing the X-type welding gun, the C-type welding gun, and the special type welding gun is installed through an arm of a robot.
Thus, a robot including a spot welding apparatus employing the X-type welding gun, a robot including a spot welding apparatus employing the C-type welding gun, and a robot including a spot welding apparatus employing a special type welding gun are installed in lines, respectively, to perform a spot welding operation.
However, in the related art spot welding operation, since a single spot welding apparatus per robot is installed in a robot arm, only single spotting welding is performed at every moment the arm of the robot moves, requiring a great amount of time to perform a prescribed number of welding point operations to degrade productivity and efficiency.
In addition, lower welding guns each having a different shape should be applied according to positions and shapes of welding points, increasing investment cost for facilities, and in particular, in a case in which a plurality of robots having a spot welding apparatus employing a lower welding gun having a special shape are in use, facility and maintenance cost is increased, energy is excessively used, and space occupancy of robots in a mass-production line is increased.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.